JIT Simulation Game ("Paper Airplane" Exercise)

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JIT Flow Simulation
AKA: The “Paper Airplane” Exercise
This is a simple, but powerful, teaching tool that allows the demonstration of nearly every
JIT principle and gives an opportunity to discuss the rest. The power is in the flexibility
of the exercise to be adapted and modified to nearly any circumstance.
These instructions are not intended to be in any way prescriptive. They are, however, an
effective and proven baseline from which to operate.
Required Number of Participants
Operators 4
Expediter/Material Handler 1
Factory Manager 1
Customer 1
Timers 2

1
Basic Exercise (45 - 60 minutes)
Materials:
60 sheets plain paper
20 sheets 3 punch paper
10 sheets colored paper
2 stopwatches
1 calculator
flip chart
two contrasting color markers
Preparation:
Pre-build four production station sets:
1. Two sheets plain (unfolded paper), one w/ fold #1.
2. Two sheets w/ fold #1; one with folds #1, #2.
3. Two sheets w/ fold #1, #2; one with folds #1, #2, #3.
4. Two with folds #1, #2, #3; one completed airplane.
Fold #1 (Op #1)
“Fold” #2 (Op #2)
(two folds)
“Fold” #3 (Op #3)
(two folds)
Thisedgeendsup
aligned
w
ith
top.
Fold winglet - bottom edge ends up along top edge.
“Fold” #4 (Op #4)
(two folds each side,
four folds total)
The content on this slide has been partially hidden.
FlevyPro members can download the full document here:
http://flevy.com/browse/flevypro/jit-simulation-game-paper-airplane-exercise-1822

2
Note: As silly as it seems, there is a reason for the folds illustrated. Using this design
ensures that there is a big enough work imbalance to make some important teaching
points, especially in the “advanced variation” at the end of this document.
On a flip chart, draw the following matrix:
Lot Size
WIP
Throughput (Lead) Time
Total Run Time
Deliveries (to customer)
# of people
Space
Productivity
(Units / Person / Minute)
Quality
Comments, Observations
Set up the exercise. This should be fun, not dry.
Run #1
Announce that we are going to demonstrate the differences between various production
systems by setting up a factory that makes airplanes. Ad lib something about the
airplanes we are making. (they don’t fly, etc.)
Ask for a volunteer for operator #1. Point out that this job requires some skill and
precision. When someone volunteers, give them production station set #1. Make a
flourish out of demonstrating how to fold the paper, ask if they understand, then ask them
to practice on the remaining sheet. They should now have three completed sheets for Op
#1.
Finished Plane

3
Repeat the process for operators #2, #3, and #4. Be sure to solicit volunteers from
different tables, preferably criss-crossing the room several times.
Solicit a volunteer to be the materials handler. A good technique if no one is forthcoming
is to see if anyone is wearing athletic shoes and “volunteer” them. Explain to the material
handler that his job is to move material “from operation 1 to operation 2; from operation
2 to operation 3, from operation 3 to operation 4 and from operation 4 to our customer.”
The customer can either be another student volunteer or a co-instructor. There is some
advantage to using a co-instructor as customer. There is less briefing involved and co-
instructors are generally more willing to be a pain to the factory manager when their
deliveries are late. Quietly brief the customer to take any but obviously misfolded
airplanes, but to object loudly if any of the airplanes made from “defective material”
should be delivered to him. Make sure the customer knows what “defective material” is.
(Another good reason to use a co-instructor as customer.)
Appoint a factory manager. Make it clear that the factory manager’s job is to “keep
things running smoothly and keep the customer happy.” Don’t let the factory manager
help out.
Timers: If you are using stopwatches, you can keep time yourself, or appoint people to do
it.
Point out that because of the distance between operations, we are building and moving
materials in lots of three airplanes. They can move any multiple of three that are ready,
but lots of three must stay together. Tell the operators that once they have completed
three parts, they are to call for the material handler to take their work to the next
operation. They should not wait for the material handler, though. If they have work
queued up, they need to keep working.
Announce that everyone else in the class is a “wastologist, someone schooled and studied
in the science of waste.” They are to identify specific examples from the “Closed mitt”
list and write them down for the debrief.
Tell them that once the system is running smoothly you will introduce a different color
sheet of paper to track how long it takes product to move through the system. They are to
treat that sheet like any other.
The customer will take all of the airplanes they can build. You (the instructor) will
supply raw material to the first operation.
Ask if there are any questions. Do not allow them to change the production layout, etc.
Only answer questions about how the factory will operate.
Announce “Go!” and start the production run timer.

4
Be sure to feed paper to Op #1 as fast as he needs it. If the operator makes an
“improvement” and starts folding three sheets at a time, praise him for his improvement,
but don’t mention it unless he thinks of it.
Operation #2 and operation #4 should back up fairly quickly. Once there is significant
WIP backed up in the system, introduce the colored sheet of paper. Start the throughput
(lead) time timer as soon as the operator touches the stack.
At this point, the customer should begin bothering the manager about when the colored
airplane will be delivered. (This is to point out schedule stability later.)
Start slipping “defective” raw material into the stack. If operator #1 is folding three at a
time, start by sandwiching the defective material between two good sheets, then intermix
stacks with no defects, one, two, or three defects. If the operator says something try to
not respond at all - sometimes their comments are just to someone else at the table. If
they get the factory manager or attempt to stop production, tell them that’s the material
you have. Try to keep it as low-key as possible.
(Note: An alternative for “defective material” is to take a stack of paper, drive a staple
through one corner and pull it out. This leaves very subtle defects.)
At some point the students usually start expediting the colored airplane. Let them, but
insist it always move as part of a group of three units. If they do expedite, let them. It’s a
good teaching point later.
When the customer gets the colored airplane, stop the exercise, and note the flow time for
the colored plane.
Debrief
(Chart filled in with example, but typical, numbers.
Obviously you use the “real” ones.)
Fill in “Run #1” at the top.
“Our lot size was three”
Ask everyone to count up how
much WIP they have. Don’t
count delivered airplanes or
raw material. Total it up and
enter the number in WIP. If it
doesn’t divide by 3, have
some fun about how THAT
could happen.
Run #1
Lot Size 3
WIP 32
Total Run Time 7:15
Throughput (Lead) Time 6:32
Deliveries (to customer) 18
# of people 6
Space 4 tables
Productivity 0.42
Quality 12

5
Ask the timer (or announce if you kept time yourself) how long it took the colored
airplane to flow through the system. If they expedited the colored plane, point out that
this is the expedited time!
Ask the customer how many airplanes were delivered.
Remind the class that we had four operators, a material handler and a manager for a total
of six people.
Say “we used four tables, so that’s good for the space” and write ‘4’ in the space box.
Calculate productivity. Tell the class we will measure productivity as “planes per person
per minute.” Divide the number of planes delivered to the customer by six (people).
Divide that result by the total start to finish time of the exercise. This number is typically
between 0.3 and 0.5.
Note: For calculation ease - six seconds = 0.1 minutes.
:06 seconds = 0.1 minutes
Ask permission from the class to round the minutes for calculation so they know what
you are doing when the numbers look different.
Ask about quality. Hold up a piece of “defective material” and ask how many pieces are
in the system. The class will have to go through a mad search to locate and find the
pieces with defective material. Point out how much time and effort they are spending and
ask them how often they go through this exercise in real life when they discover a
problem. Write the number of defects in the box.
Ask everyone “What was it like to work here?” Try to facilitate the group through
understanding: Stress, chaos, no communication, didn’t know how much work to do, etc.
Ask the “wastologists” what they observed, record their comments on the flip chart.
Ask them where the bottleneck is in the process. Most will agree it is either operation #2,
operation #4 or both.

6
Run #2
Ask the class what we can do to fix some of the problems.
They will nearly always suggest putting the operations closer together.
Clear off a table (if you haven’t done so already), and seat the operators around it in
order. (Preferably with production going counter-clockwise if the table permits.) Seat
the customer next to operation #4. Tell the material handler that he will be kept on the
payroll and moved to another job.
Ask the rest of the class to gather around so they can see what is happening.
Ask what would happen to the WIP levels if we just ran the exercise again? You may
have to lead them through understanding that they would rapidly build up again (maybe
more rapidly) and the total lead times probably wouldn’t be much better.
To avoid that problem, some system has to be put in place to manage how much WIP is
allowed to build up in the line. We are going to use a pull system to regulate each
station’s production.
Place a sticky-note between each person at the table.
Explain the role of the “kanban square” as a means to regulate overproduction - the worst
of the ten wastes.
Each operator LOOKS RIGHT, and if there is no WIP on that square, pulls work in
FROM THE LEFT.
Tell the customer NOT to take any planes from the square, and have the operators
practice the kanban rules by building. As the planes work their way around, watch
operator #1 and #2. Their pace will be slowed when Operator #4 gets the first plane.
They will be tempted to pull work in early. Stop them!
When the customer’s kanban gets the first plane, all work should stop.

7
Start the exercise by having the customer pull the
plane off the kanban, start the elapsed time.
After they have established a rhythm (six or
seven minimum planes to the customer),
introduce the colored sheet and start the lead-time
timer.
Stop the exercise when the customer pulls the
colored airplane off the last kanban. Stop both
timers.
Focus the attention of the class back to the chart
at the front and begin collecting the statistics.
Sample Data - Your Mileage May Vary
Ask how much WIP is on
the table (not raw material,
not customer delivered
planes). It will be 3 or 4.
Ask the MAXIMUM WIP
level that will ever develop
in this system. (4). Ask
what is the maximum WIP
level that could develop in
the “traditional” (Run #1)
system - infinite - there is no
WIP management.
Record the measured throughput time. Ask how long another plane will take? (Same).
Ask how long EVERY plane will take. (Same). How about the first run? Remember -
they probably expedited that one. How long does it take? (No one knows, and it varies
with the amount of WIP in the system.) Lead time is directly related to the amount of
WIP in the queues. If WIP isn’t regulated, there is no way to predict flow time for a
particular item.
Point out that the material handler’s job is no longer required here, and the manager’s job
is significantly reduced because there is less intervention to do. The manager can spend
more time and attention on improvements and prevention and less on fighting fires.
Calculate productivity the same way as above. It will be significantly higher. Calculate
the productivity again, using six people. It is STILL higher about 80% of the time. This
proves that the productivity gain wasn’t just in eliminating the person from the loop.
Customer
OP #1
OP #2
OP #3
OP #4
Raw
Material
“Kanban”
square
Run #1 Run #2 Delta
Lot Size 3 1
WIP 32 4
Throughput (Lead) Time 6:32 1:12
Total Run Time 7.15 1:65
Deliveries (to customer) 18 10
# of people 6 5
Space 4 tables 1 table
Productivity 0.42 1.21
(.85)
Quality 12

8
Ask about quality. Hypothetically, if the “bad material” had found its way all the way to
the customer, what is the worst case for defects? (4). In the worst case, how long until
the system can start delivering again once it starts up? (lead time, in this example, one
minute, twelve seconds.) What about the first case? Not sure.
Ask about the differences in the working environment.
(Less stress, better communication, etc.)
Ask the wastologists what they saw. They should have spotted the fact that most
operators were spending a lot of time waiting in this case, where they were busy in the
first case.
Ask if their work statement has changed. (No). The point is - When the chaos and
queues are cleared out, it is easier to see what is happening. The work imbalance existed
in both cases, but now the bottleneck (Op #4) is obvious.
What to do about it depends on whether the system was meeting customer demand or not.
If it was delivering fast enough, then improvement activity should focus on combining
operations in the first three ops rather than taking work away from #4.
Point out that without knowing customer requirements, it is impossible to determine what
improvement activity is necessary. This is a segue into takt time and work balancing in
the Continuous Flow material.
See “Advanced Variation” to make these last points more effectively.

9
Advanced Variation - Takt Time and Work Balance
During Run #1 observe Operator #4. If he is taking significantly longer than 15
seconds to do his folds, you will have to modify the presentation to start with doing
improvement activity on Operation #4 before immediately redistributing the work.
When setting up Run #2, explain that the customer’s true requirement is one plane every
15 seconds. Explain that this is called the takt time, and reflects the customer’s rate of
consumption. Instruct the customer to take an airplane no more often than once every 15
seconds and give her a watch with a second hand if she doesn’t already have one.
Do Run #2 as outlined above only with the takt time restriction.
Covertly calculate the RATE OF PRODUCTION from Run #1. (Planes Delivered / Total
Elapsed Time) This is typically about 3/minute. I have never had it exceed, or even
meet, 4/ minute.
During the outbrief:
Go through the same metrics as above.
Ask about the bottleneck. Most people will begin to suggest leveling the work to reduce
operator #4’s workload.
Point out that, based on the customer’s true requirements, Operator #4 kept up and does
not need to work faster.
Ask, again, what would the next improvement activity be?
(Usually a rhetorical question on your part - there is rarely an answer that isn’t grasping
for something.)
Explain the work balance chart as
you draw it on the flip chart. Use a
different color (red) for the takt time
line.
Explain that, because of exhaustive
data collection, we know the cycle
times for each operation in the paper
plan factory. They are:
Op #1 3-4 seconds
Op #2 7-8 seconds
Op #3 7-8 seconds
Op #4 12-15 seconds
takt time = 15 sec

10
Point out that only by knowing this information and the takt time can management make a
good decision about how to improve performance.
Add bars reflecting the cycle
times to the chart.
Ask again, where should we
improve?
Many people will still want to
level-load operations 1, 2, 3 and
sometimes all of them.
Others will suggest combining
operation 1 with operation 2.
Point out that while that would
free up another operator, it would
require major work to make
further improvements.
takt time = 15 sec
1 2 3 4
takt time = 15 sec
1 2 3 4
takt time = 15 sec
Point out that if Operation 2 and
3 total less than the takt time that
we could reallocate another
operator and improve
productivity by another 25%. If
it was close, as illustrated here, it
would require only a very small
improvement in the cycle time to
get the benefit.
takt time = 15 sec
1 2 3
1 second improvement will free an operator.

11
That leaves us with operator
#1 with three seconds of
work. If we can somehow
improve the process and
remove three more seconds,
that would let us build to the
customer’s requirement with
two operators, not four.
Only by thoroughly understanding the cycle times and the takt time is it possible
to see the resources that are really required to meet the customer’s requirement.
Without that information, we are managing blind.
What would be the consequences if people who didn’t look busy all of the time
were told to “get to work?”
We would never see the idle time that is available, and would assume we needed
more capacity, when in reality, there is too much. We would never see that by
saving a total of four seconds from the combined cycle times we can reallocate
50% of the operators.
By making sure people “stay busy” you are depriving yourself of information you
must have to make rational management decisions.
Takt time is one of the most powerful management tools available, and is the
heart of managing a JIT production system.
takt time = 15 sec
1 2 3
3 second improvement will free another operator.

12
Further Advanced Variation – Heijunka or Load Levling
During Run #1 the demand is for 6 Blue colored planes and 6 Red colored planes and 6
yellow colored planes. This round is a batch mode, i.e., all blue colored planes are made
in lots of 3 together and then the red colored planes and finally the yellow colored planes.
Note the time taken to fulfill the customer demand in a given time period. Customer may
not receive all he/she wanted and hence we have an unhappy customer!
During Run #2, mix colors and use one piece flow.
Note the deliveries to the customer. Customer should get all the required quantities in a
shorter time frame and also all the different colored planes he/she ordered.

1
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